STRUCTURE-LUMINESCENCE CORRELATIONS IN PROTEINS

  • Prendergast, Franklyn G (PI)

Project: Research project

Project Details

Description

Fluorescence spectra, quantum yields and lifetimes have often been used as
predictors of the location of a fluorophore in the protein matrix. The
implicit assumption in the use of fluorescence data in this manner has been
that water is the major determinant of fluorescence emission properties
especially of spectral position. Molecular graphics data coupled with
fluorescence data show that there is no simple way to correlate
fluorescence properties with either location of the fluorophore in the
protein matrix or accessibility of water to the fluorophore. We propose
now to extend the studies on protein structure-fluorescence correlations by
performing extensive measurements of fluorescence properties and
calculations of molecular electrostatic potentials of the tryptophan
environs and using molecular graphics techniques to depict environs and
electrostatic potential profiles. We will study proteins containing single
tryptophan residues primarily, but will in some instances also study
proteins with multiple fluorophores where the fluorescence of each emitter
can be resolved. An especial effort will be made to determine if radiative
lifetimes provide the most meaningful decay parameter for evaluating
environmental effects on protein fluorescence. Environmental effects will,
in turn, be assessed by measurements of apparent dipolar relaxation rates
and time resolved emission spectra at room temperature and in the
ultracold. Most proteins to be studied will be of known crystal structure.
We hope, thereby, to verify the roles of amino acid sidechains, of other
groups in the protein matrix capable of forming exciplexes or of quenching
and of water accessibility in determining the fluorescence properties
evinced. The molecular graphics data will also allow depictions of the
intraprotein volume available to a fluorophore for movement. Time resolved
fluorescence anisotropy measurements will be used to verify the rate and
extent of motion of the fluorophores independent of whole protein rotation
in the picosecond to nanosecond time domain. We will try to correlate
oxygen quenching of protein fluorescence with the packing density around
tryptophan moieties. An attempt will be made to correlate the experimental
data and the molecular graphics depictions with results from molecular
dynamics calculations as the latter become available.
StatusFinished
Effective start/end date8/1/856/30/03

Funding

  • National Institutes of Health
  • National Institutes of Health: $362,139.00
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health
  • National Institutes of Health: $353,232.00

ASJC

  • Medicine(all)
  • Biochemistry, Genetics and Molecular Biology(all)

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